1. Field of the Invention
The present invention relates to fluid dispensing apparatuses and, more particularly, to a liquid spraying apparatus which is environmentally safe.
2. Description of the Prior Art
Aerosol cans are well known as conventional liquid spraying apparatuses of everyday use. In conventional aerosol cans, the liquid to be sprayed is directly mixed in a single chamber of the container with a propellant, which is generally an inert gas such as chlorofluorocarbons (i.e. CFCs), whereby the liquid does not react with the propellant. CFCs have been widely used as refrigerator coolants, spray can propellants and foaming agent. CFCs being stable gases have a chemical inertness which is the source of both their usefulness and their danger. They do not react with, for instance, the deodorant they are meant to spray, but they can also spend years rising through the atmosphere without breaking down. However, when the CFCs reach the stratosphere, their chlorine atoms react with ozone to create conventional oxygen and chlorine monoxide. The chlorine monoxide then reacts with maverick oxygen atoms to form conventional oxygen and another chlorine atom, and so on. A single chlorine atom can destroy thousands of ozone molecules.
When the spray tip of such an aerosol can is actuated, the CFCs cause the liquid to atomize with both being discharged from the spray tip. Therefore, the harmful CFCs are emitted in the atmosphere where, as it is now widely known, they damage and even destroy the ozone layer of the atmosphere thereby contributing to the greenhouse effect. Furthermore, containers operating with CFCs cannot be refilled nor recycled.
Following pressures from the population, aerosol cans using CFCs have been eliminated from the market in most part.
To overcome these disadvantages, the vaporization or atomization of the liquid contained in some prior art containers resulted from an inert gas dissolved in this liquid. Such containers responded adequately to the problems generated by the use of CFCs although they suffer from further problems such as, for instance, a non constant stream due to the gas pressure progressively decreasing in the container.
To prevent the propellant from discharging with the liquid, containers were developed having a pair of separate chambers respectively containing the fluid to be dispensed and the propellant, as disclosed in U.S. Pat. No. 2,823,953 issued in 1958 to McGeorge. Indeed, McGeorge discloses a container having a flexible bag hanging therein from an exterior wall thereof. The flexible bag contains the liquid to be dispensed from the container. A compressed gas exerts within the container a pressure on the walls of the flexible bag. The container includes a removable cover that allows the flexible bag to be filled up once emptied. The bag and the cover are adapted to form a seal between the content of the flexible bag and the exterior of the container. An admission valve is provided to allow the container to be filled with the compressed gas.
Again, the main disadvantage of the above container lies in that the pressure exerted by the gas on the flexible bag progressively decreases as the bag is emptied. Therefore, the atomization of the liquid contained in the bag is not constant during each cycle of the container.
Moreover, the container being refillable, it is preferable that the bag, which may be discarded in the event, for instance, where a new fluid is intended to be used, be designed to be easily mounted to the container.